1. The problem statement, all variables and given/known data The coordinates of the parallelogram ABCD are: A (-2; 1) B (5; 2) C (6; 5) D (-1; 4) We also know that the diagonals intercept in the middle of each other (so if the diagonals are AC and BD, and the intercept in point M, then AM = MC, and BM = MD). Not sure if this information is useful or not though. 2. Relevant equations Area = base * height 3. The attempt at a solution So...yea, no clue actually. I know how to calculate AB = CD = (...) = 5√2 Likewise, BC = AD = (...) = √10 For what they're worth: AC = 4√5 BD = 2√10 I tried googling around for an answer, and everyone seems to solve it with these steps: - Calculate the line passing through A and B - Calculate the distance between point C (or D) and the line passing through AB; this gives you the height - Do AB*height However, we didn't do lines equations at school, so this assigned problem should probably be done in some other way (Pythagorean theorem, distance between two points, middle point of a segment).